After extensive laboratory experiments, preliminary clinical trials have shown it is possible to obliterate cerebral aneurysms and arteriovenous anomalies by low-risk techniques that involve a simple arterial puncture instead of major brain surgery. Originally begun as a project using magnetically-tipped catheters to achieve these goals, other unique and promising techniques have evolved. These include the use of magnetic emboli and intravascular sleeves. In collaboration with the Francis Bitter National Magnet Laboratory at the Massachusetts Institute of Technology, we propose to bring to full fruition these capabilities in man.